Desaturated video after rendering
Since all outputs and original video opened in QT and Blender is "desaturated" in the same way, I would say that it is more like wrong interpretation of colours in VLC. There is also noticeable contrast in VLC that totally flatten black parts (hairs) = loose all the rest of details that wasn't destroyed by camera and compression already.



Original video and rendered VSE PNG inside Blender ...


... they perfectly match (top row on bottom row with blend type - Different). I used curves to bring contrast in extreme values to see result better. Completely black.


BTW also your screen of PNG's match perfectly.

But result differs when the same data (video and render is opened in VLC.


Rendering into QuickTime H.264, opened in QT, produce differences only due compression artefacts.